Control apparatus



y 5, 1958 R, E. MlCHEL 2,833,875

CONTROL APPARATUS Filed Dec. 14, 1953 4 Sheets-Sheet 1 A? INVENTOR.

; RAYMOND E. MICHEL T98 I E. fiy

ATTORNEY May 6, 1958 R. E. MICHEL CONTROL APPARATUS 4 Sheets-Sheet 2 Filed Dec. 14, 1953 IN VEN TOR.

ATTORNEY- J M M m 2 B TORQUE mcu LBS.

Filed Dec. 14, 1953 4 Sheets-Sheet 3 INVENTOR.

RAYMOND e. MIG-EL ATTORNEY y 5, 1958 R. E. MICHEL 2,833,875

CONTROL APPARATUS Filed Dec. 14, 1953 4 Sheets-Sheet 4 INVENTOR. 'RAYMONDQE. MICHEL ATTORNEY United States Patent CONTROL APPARATUS Raymond E. Michel, St. Louis Park, Minn, assignor to Minneapolis-Honeywell Regulator Company, Minna apoiis, Minn., a corporation of Delaware Application December 14, 1953, Serial No. 397,882

lfiClaims. (Cl. 200-146) The present invention relates to an improved apparatus for decoding a punched tape.

While punched cards are commonly used for classifying and recording information, a punched tape has advantages for some purposes by insuring against improper feeding of cards, mixing of sequence and the like. Handling the punched tape properly, however, involves problems not generally encountered with cards. The present invention solves the problems associated with the handling of a punched tape by providing improved tensioning means for the tape, improved pin retraction means, improved switch means and other improvements all contributing to the practical operation of such a device. The improved tensioning mechanism maintains a uniform tension on the tape at all times and thereby aids greatly in mm'ntaining the accuracy of the tape and its punchings.

The improved pin retraction means is elfective to retract a large number of spring biased pins with mechanism having a motor with much lesstorque output requirement than the spring loaded pins require due to a load transferring mechanism, thus permitting rapid and accurate functioning of this mechanism and minimizing wear and tear on the tape, the intermittently movable tape moving only when the pins are retracted. The improved switches are, because of their large number, necessarily compactly arranged in space difficult of acess but are easily and dependably operated, with the improvements in operation permitting relatively light springs for the actuator pins and thereby contributing to the fast and dependable operation of the present mechanism. Also, by using a double contact arrangement, the dependability of the switches is considerably improved. Other improvements such as the manual adjusting or operating means for the tape permit quick alignment for starting, a ready return for repetition of a section or other such operations.

It is thus an object of this invention to provide an improved apparatus for making available or reading information on a punched member.

More specifically, it is an object to provide apparatus for reading a section at a time of a punched tape and moving from one section to another accurately and with a minimum of delay.

It is still another object to providea punched tape decoding apparatus that is rapid and accurate and which, by the low stresses imposed on the tape, preserves the accuracy of this member.

These and other objects will become more readily apparent upon a study of the following specification and drawings wherein:

Figure l is a plan view of the present decoder, with parts broken away.

Figure 2 is a right side elevation of the present mechanism. 1

Figure 3 is a front elevation of the decoder with the front plate removed.

Figure 4 is a left side elevation of the apparatus.

Figure 5 is a schematic, view showing the. path of the ice tape, showing the pin and switch mechanism and showing the differential mechanism of the tape tensioning means.

Figure 6 is a circuit diagram of the apparatus.

Figure 7 is a stress-strain diagram showing the stresses involved in retracting the pins and also showing the counterbalancing forces.

Figure 8 is a schematic view of the retraction damper mechanism Figure 9 shows a modification of a detail.

The present tape reader or decoder comprises a framework or chassis it) serving as a mounting for the equipment to be described. Chassis 10 is attached by bracket members 12. and 12 to rails 13 and 14 which slidably support frame it) in a control panel, not shown, of the sort described in copending-applications, Serial No.- 170,971, filed June 29, 1950, and Serial No. 364,868, filed June 2.9, 1953.

The chassis 10, as perhaps best shown in Figures 1, 2 and 5, supports an upper or supply tape holdingroll l7 and a lower roll 18, shown in Figures 2 and 5, these rolls being pivotally mounted by, on one side, spring positioned retractable pins i9 and 20, Figures 1 and 4, and

on the other side by drive pins 21 and 22, splined to gears 23 and 2d, respectively. in addition, ratchet Wheel 25 is attached to shaft 21 and ratchet wheel 26 is attached to shaft 22, these ratchet wheels being engageable with mating ratchet member 27 and a like member, not visible,

.carriedby manually operable latch members 29 and 3h,

these latch members being adjustable from a position wherein 25 and 217 and 26 and itsmating member are engaged, as shown, to opposite positions in which the ratchet members are not engaged and the rolls are free to rotate. In the engaged position rolls 1S and 19 are also removable and a tension spring, to be described, is locked to prevent unwinding.

. The punched tapefil, shown in side elevation in Figure 5, is puched in sequentially disposed areas and thus, in effect, duplicates a succession of punched cards. The tape 34 is trained, from supply roll 17, over an idler roll 35 down across a perforated plate 36 disposed on the front side of chassis 10, around sprocket wheels 37 and back to the other or take-up roll 18. In addition to sprocket wheels 37, support wheels 38 arearranged between the sprocket wheels to prevent the tape from buckling. The sprocket wheels 37 engage perforations, not shown, along the opposite edges of tape 34 and thus transmit the driving force available for transferring the tape from one roll to the other and for sequentially moving the tape portions across plate 36.

Tension is maintained ontape 34 by biasing both rolls 17 and 18 in a-direction to wind tape thereon, the bias on roll 17 thus being against the driving force exerted through the sprocket Wheels 37. The bias tension is exerted by a spring 41 wound around a driving drum 42 and a rotatable cylinder Spring 41, of a sort having substantially a zero spring rate, as used, and referred to in the trade as a Negator spring, has, inherently, a greater tendency to Wind on the small cylinder 43 than it has on the drum 42 hence, 23 in Figure 5-, looking from roll 18, drum 42. tends to be driven in a clockwise direction. In Figure 5, cylinder 43 is located to the'ieft of drum 42 but this inconsistency with the other figures is merely for convenience and it should be assumed that drum 42 is biased in a clockwise direction, as above. As shown in Figure 5, drum 42, through differential gears 44, biases gears 45 and 456. and thus shafts t! and 43, respectively, Shaft 47 drives gear 49, meshing with gear 23, in the same direction as drum 42 tends to be driven and thus tends to drive roll 17, in Figure, 5,, clockwise. Shaft 48 drivesgear 50, meshing with gear 24*, in a similar direction, and thus tends to drive roll 18 in a counterclockwise direction. When the effective diameter of rolls 17 and 18 is equal, due to equivalent lengths of tape wound thereon, rotation of a roll in one direction so as to unwind tape therefrom, due to movement of the tape, is accompanied by rotation of the other roll in a direction to wind tape thereon and without an movement of drum 42. However, as the relative effective diameters of the rolls change, the difierence in motion is accommodated by motion of drum 42, the drum tending to unwind spring 41 as roll 17, due to a larger efiective diameter when full, requires that roll l8 rotate at a greater velocity to take up the tape on the smaller effective diameter of roll 13 and drum 42 tends to rewind the spring 41 as roll 17 transfers tape past the point of equal effective diameters and the diameter of roll 18 becomes larger than 17. However, during this winding and unwinding of drum 42, the tension exerted remains practically constant because of the Zero spring rate characteristics of the Negator spring.

Referring back to the manually operable latch means 29 and 36, it will now be apparent that the principal utility of the latch means is the preventing of the unwinding of the bias spring 41 when rolls are changed and at other times when it is desired that the rolls remain free of the tension device and thereby free to rotate during tape installation in the decoder.

The principal function of the present mechanism is the proper reading of punched data in the tape and the concurrent operation of a great many switches, the present apparatus having, as schematically suggested in Figure 3, 43 vertically arranged rows of switch actuating pins, each row including pins for a total 430 switch actuating pins, each pin being connected to an individual switch. These pins, identified generally as 53, are each connected by a flexible connection means 54 to its individual switch 55. As schematically shown in Figure 5, with one of switches 55 being enlarged for convenience in showing and most of the switches being omitted because of the confusion that would result if all were shown, it will be noted that each of switches 55 includes a pair of stationary contacts 56 somewhat resiliently mounted and connected to a connector terminal post 57. A pair of movable contacts 58 are connected to a block 59 connected by a resilient member 64) to a connector terminal post 61, the contacts being so arranged that they make and break in sequence and operate in parallel and thus give assurance of a good connection. As one set of contacts makes first and breaks last, arcing is concentrated on it thereby protecting the other set of contacts. The block 59 carrying the movable contacts 53 has a socket portion 62 in which one end of the flexible connection means 54 is anchored. As a modification, shown in Figure 9, connector 54 may be attached to switch arm 60 by a nylon member 63 having side notches 7d, the notches 70 receiving the lower ends of member 60 forming the sides of slot 73, notches 70 having knife edges 76 for bearing against member 60. Block 59 is preferably of an insulating plastic material and connection means 54 is preferably a piano wire having a ball portion on each of its ends formed by heating the end ofthe wire to a melting point and thence removing the source of heat. By this simple operation, a very nearly round ball is formed which is ideal for the present purpose in that it gives an easily operable flexible connection between means 54 and block 59, uses ery little room and is dependable. The other end of connection means 54 is likewise formed with a ball which engages a socket portion 64 of a member 65 threadedly at-- tached to the rear end of a pin 53. Obviously, any other suitable connection means may be used.

Each of pins 53 has a flange 66 engaging a coil spring 67 which urges the pin to the left, as shown in Figure 5.

a further flange 71 engageable by a retractable plate 72. In ddition to guide means 63 and 69 for the pins, each of the pins also goes through holes provided in plate 72 and additionally through registering holes in a front plate 36 shown in Figures 5 and 3, with registering holes also being provided in front plate 74, the holes in front plate 74 being terminated short of the front face and being deep enough to permit a full leftwise travel of pins 53 so that the switches 55 may close their contacts. Front plate 74 is spaced from plate 36 by a distance sufiicient to permit feeding tape 34 therebetween. The pins 53 are so proportioned, and the collar 66 and 71 are so correlated with plates 68 and 72 that, when the pins 53 are stopped by paper 34 between plates 36 and 74, they can not be moved far enough to the left to close the switch contacts hence they remain open. In Figure 5, both switches 55 are shown closed because the pins 53 have moved the maximum distance to the left. Obviously, those pins unable to move to the left because of intervening unpunched tape can not close their associated switch contacts. The connector'pins shown in Figure 5 are all connected by a wiring harness to a connector block 75 shown in Figure 1, this connector block being adapted to be connected to a mating connector member from which connections to control apparatus may be made. The connections have not been shown because of the confusion that would result.

It was mentioned above that plate 72, through which pins 53 extend, is retractable and, as shown in Figure 5 it will be noted that plate 72 is connected by strap means 78 and 79 to pivoted arms 84) and 81, respectively. Arm 80 is adjusted by a cam means 82 and arm 81 is adjusted by a cam means 83, the arms being shown in a non-retracted position in Figure 5. Cam means 82 and 83 are simultaneously operable by an electric motor 84, in Figure 2, driving through a worm gear SS and a pinion 36, a gear train identified generally as 88 and including gears 89 and 90, gear 89 driving eccentric 83 and gear 90 driving eccentric 82, the gears 89 and 90 operating in opposite directions and at the same speed. Obviously, one revolution of gears 89 and 0 and their associated eccentrics 83 and 82 will move plate 72 through a initiating signal.

The pins 53 are all slidably guided in a pair of spaced complete cycle of retraction and extension of the pins. A homing switch of a conventional sort, identified as 92, is carried on the same shaft as gear 89 and, upon an initiating signal for motor 84, continues the operation of motor 84 until gear 89, and thus gear 90, has made a complete revolution and then stops to await a further Homing switch 92 is schematically shown in Figure 6 and, when switch 96 is closed, as it is normally, a relay 97 is operable from a circuit including a source of current 98 to energize the motor 84 through its circuit when an initiating switch such as 99 momentarily completes a circuit and thus the initial movement of motor 84 then makes switch 92 operable to carry on the operation for a complete revolution. Switch 99, any initiating switch, is one of several switches connected in parallel for operation of the motor 84 by the above described circuit in response to initiating signals from the system disclosed in the previously referred to appli cation. Operation may also be initiated by a pushbutton switch 94. A lockout relay $1, normally closed, opens after sequence starts and remains open until conditions are again balanced. A slow operating relay $3 prevents more than one sequence change if manual button or initiating switch is held closed. For a more complete description of this motor control circuit, reference is made to the aforementioned application Serial No. 364,868, filed June 29, 1953.

While the present apparatus has a total of 430 switches individually operable by corresponding pins, it is to be noted that ordinarily from 20 to 50 switches are all that are operated at any one time by their respective pins, this being the normal punching of the tape controlling the number of pins that will operate their switches at any particular sequence. Thus, most of'the pins will be normally held retracted by" the presence of the tape between plates 36 and 74. Them-upon considering the effort required to rotate eccentrics 82 and 83, it will be noticed that the initial retracting movement of plate 72 will push from to 50 pins against their individual springs 67. The torque required to move back these pins to the point where all of the pins are picked up is shown graphically in Figure 7 by portion 101 of torque curve 102. Obviously, when the balance of the 430 pins are picked up by plate 72 in its retracting movement, the power or torque required rises rapidly, as shown by portion 103 of the curve until a maximum torque is reached at point 104 where the eccentrics 83 and 82 reach a point in their rotative travel wherein the rate of advance of plate 72 is slowed, the rate of travel of the plate gradually decreasing asa dead center posi-.

tion 180 removed from the position shown is reached at which point there is little effective torque required other than for taking care of friction. .As the eccentrics 82 and 83 continue rotating, and they will go through 360 travel for each cycle, the pins are again permitted to move to the left as plate 72 moves to the left. When the eccentrics 82 and 83 go past the dead'center position, and because the entire 430' pins are pushing against the plate, they tend to cause motion of" the eccentrics 82 and 83 in advance of the motor and to thus drive the motor, this being illustrated by the portion 1050f the curve 102, this tendency to drive the motor being most pronounced during the rapid change portion of the eccentric and reaching a maximum at point 106 wherein the rate of travel of plate 72 caused by the eccentrics is slowed. From this point on, the spring force is decreasing and the effective leverage of the plate 72' is reduced; Obviously most of the pins will eventually be stopped by the un'pun'ched portions of tape 34"with the tendency to cause further movement of the motor by the pins not stopped being illustrated by portion 107 of the curve 102, the abrupt drop oif from point 106 to portion 107 being due to the pins hitting the paper and thus having no further influence relative to plate 72. With the great variations in torque required forretra'c'ting plate 72, it is obvious that considerable power'is required not only to'retract the pins but also to keep in control of the pins on the forward motion of therrn If this added p'ower'were to be obtained by using a larger motor, it seems obvious that size ditficulties would arise and the inertia affects become quite pronounced as the motor size is increased. It was found, however, that this difficulty could be removed by providing a torque balance means for storing surplus energy and then using this surplus energy to help drive the eccentrics 82 and 83 when driving is required. Thus, a proper torque balance means would provide a mirror image of force relative to curve 102, this mirror image being shown by-the dotted line 108 in Figure 7. This mirror image of force is obtained by mechanism including a pair of pivoted arm members 111 and 112 urged apart by a compression spring 113, arm member 111 having an arcuately shaped shoe portion 114 and arm 112 having a similar shoe portion 115, the arcuate surfaces-being formed with a radius equivalent to the radius plus the eccentricity of the eccentrics 1-16 and 117. Shoe portions 114 and 115 are, due to spring 113, held in engagement with eccentrics 116 and 117, respectively, eccentric 116 being. carried by the same shaft as eccentric 83 and eccentric 117' being carried by the same shaft as eccentric '82. As a further means of modifying the force requirements, eccentric pins 118 and 119 are connected to eccentrics 11 6 and 117, respectively, and these eccentric pins are connected by a tension spring 120 having lost motion slot connecting means 121 and 122 so that the spring is effective only when the eccentric pins separate a greater distance than shown and being ineffective to modify motion as the eccentric pins tend to approach each other, from the position shown. In addition to the pivoted arms-1 1:1- and 112, additional arms 1:24 and 125 are also pivoted to the chassis and are urged together by a-te'nsion spring 126, the inward motion of these arms being limited by stop means comprising a spaced rod 127 and a bracket such as 128 attached to the chassis 10. Arms 1'24 and 125 each carry a pair of cam follower rolls 130-for engaging the eccentrics 116 and 117 when the eccentrics are sufficiently rotated to enage the rolls. vTo give a somewhat better schematic showing of the above described apparatus, it has been somewhat schematically shown in Figure 8. With this apparatus, such as described, and by a judicious selection of springs and a correct adjustment of the eccentrics, force is both absorbed and delivered by this torque balance means along a curve such as 108 of Figure 7 and very closely resembles the mirror image of curve 102, thusminimiz'ing the size of motor neededat 84, providing a constant operating'velocity, and thereby keeping inertia forces at a minimum. In addition, out only is the power requirement kept low but the driving motor is always in control of the apparatus because the great force of the many pin springs is harnessed for useful work rather than 'merely' tending to drive motor 84 out of control.

tape 34 by one sequence step.

Obviously, the more perfectly the springs are selected, the eccentrics adjusted, and other parts proportioned, the more exactly the force requirements of the drive mechanism can be matched but, to the extent that the motor is able to keep in control of the apparatus, great precision in this power matching is not ordinarily required since the motor, being of series type, is large enough to take care of considerable variations in load which will only slightly change the speed of retractionand extension of the plate 72.

At the same time that the pin retracting plate 72 is being operated, gear sector is being driven along with gear 89, as they are on the same shaft. At a point where all of the pins are picked up and moved back so that no pins are in engagement with the paper, gear sector 135 moves into engagement with gear 136, gear 136 having two portions with normal gearing separated by a pair of enlarged diametrically opposed teeth 137. The gear portions between the large teeth 137 are just sufficientto mesh with the teeth of 135 and to rotate sprocket wheel 37 one-half turn and thereby advance In addition to gears 135 and 136 for intermittently driving sprocket 37, a member 138 having oppositely disposed arcuate faces 139 is p'rovided, these arcuate faces after each half revolution, engaging-a circular face 140 on a member carried between gears 89 and 135 and having a recessed portion 141 permitting. plate 138 to turn one-half revolution while gears 135 and 136 are in operative engagement. This will be recognized as a conventional intermittent gear drive.

As with most complex apparatus, it is sometimes desirable to position the apparatus manually and, for this purpose, a manually usable crank member shown in part as 145, which when pushed in, extends a spring loaded shaft to operate a switch actuator 147 and a disengage ratchet from the motor drive gears and a bevel gear coacting with bevel gear 146 connected with an idler in the gear train between gears 89 and 90. Then, by operation of the crank 145, the decoding mechanism can be operated. Operation of 14"! drives switch 96 to an open position thereby preventing operation of the drive motor during the time the apparatus is being manually actuated. Thus, in all normal operation, switch 96 is closed.

For all normal operation, it is important that gears 89 and 90 revolve in a proper direction but, under some conditions, it is desirable to reverse their motion, so that the tape 34' can be wound back for repeating a sequence or the like. A ratchet member 14-8 normally engages a ratchet wheel 149 to insure a proper direction of rotation, the member 148 being held in operative position by an over center bowed spring 150. However,

by pushing in push button 151, an extension of which engages an upstanding arm 152 integral with number 148, the spring 150 can be pushed past center and then hold the member 148 in an inoperative position, thus permitting a reversal of the direction of operation of gear 99. When ratchet member 148 is raised to this second position, wherein it is inoperative to engage ratchet wheel 149, an arm 153 also attached to member 148 is moved into an operative position, wherein, upon approximately 369 movement of gear 90, a stop member 154 carried by ratchet wheel 149 engages arm 153 and rotates it counterclockwise to thus snap the ratchet member 148 and the bowed spring 159 into its normal operative position. While pin 151 can again be pushed to permit further reversal of movement, it is noted that this mechanism permits only one turn of reverse motion of the drive apparatus at a time, and, by so limiting the motion, the sequence of the tape punchings is preserved.

Although the present apparatus has been described in considerable detail and also incorporates several features of interest that have not been fully described, it is rather apparent that many substitutions and equivalents may be used. Because of this, the scope of the invention should be determined only by the appended claims.

I claim:

1. Apparatus of the class described comprising, in combination: a bank of aligned reading pins; means mounting said pins in selected relative positions for individual axial displacement; a spring acting axially on each of said pins to urge it into a normal position; a backing plate having a field of openings whose relative positions are the same as those of said pins; means mounting said backing plate adjacent said bank of pins so that one end of each pin, in the normal position thereof, enters an opening in said plate; means for simultaneously retracting all said pins to displace the ends thereof out of said openings; a record strip having fields of perforations whose relative positions correspond to those of pins in said bank; means for guiding said strip along said plate on the side thereof adjacent said bank of pins; a feed roll and a takeup roll for said strip; means including a drive roll spaced along said strip between said feed roll and said takeup roll for advancing said strip intermittently and incrementally to align successive fields of perforations therein with the pins of said bank; spring torque motor means acting on said feed and take-up rolls to maintain the tension in said strip on the feed side of said drive roll equal to the tension in said strip on the takeup side of said drive roll; means immobilizing .said torque motor means to permit removal and insertion of different records strips without loss of torque; torque balancing spring means; motor driven means connected to said retracting means and said torque balancing spring means for first retracting all said pins and simultaneously allowing said torque balancing spring means to expand, and advancing said strip to align a new field of perforations with said bank of pins, and finally allowing said pins to return from their retracted position and simultaneously compressing said torque balancing spring means; and means in the connection between said motor means and said torque balancing spring means for abruptly changing the eifective spring rate thereof.

2. Apparatus of the class described comprising, in combination: a bank of reading pins; means mounting said pins in selected relative positions for individual axial displacement; first resilient means urging said pins in a first axial direction into operative positions; retracting means operable in opposition to said last named means to simultaneously displace all said pins axially into an inoperative position said retracting means including motor means and a second resilient means substantially equal to and opposing said first resilient means; control means actuated by said reading pins when fully displaced in said first direction; a record strip having fields of perforations whose relative positions are identical with the relative positions of pins in said bank; means normally positioning said strip adjacent said bank of pins to prevent said pins from being fully displaced in said first direction by said first resilient means, except when a perforation in said strip is aligned with one of said pins, so that actuation can take place only of the control means associated with pins aligned with perforations in said strip; means including said motor means for advancing said strip in discrete increments to align successive fields of perforations with said bank of pins; and sequencing means for first causing operation of said retracting means, then causing operation of said strip advancing means, and finally disabling said retracting means.

3. Apparatus of the class described comprising, in combination: a plurality of spring pressed members each having a position of minimum spring force; means normally maintaining all but a small minority of said members in a position of greater spring force; retracting means operable on said members to compress the springs of first said minority of members and then of all said members so that the spring force against said retracting means is irregular with displacement of said member; means including a rotatable shaft for causing operation of said retracting means through a cycle of compression and release of the springs of said spring pressed member, the torque required on said shaft varying irregularly through said cycle; motor means for driving said shaft; 21 further resilient member; means for compressing said member; and means causing operation of said last named means in accordance with rotation of said shaft in such a fashion that the torque on said shaft required therefor also varies irregularly through said cycle in a manner opposite and substantially equal to the torque required by said actuating means, whereby the efiective torque required of said motor is rendered substantially uniform and therefore rendering motor speed nearly constant throughout said cycle.

4. Apparatus of the class described comprising, in combination: a supply roll; a takeup roll; a strip wound upon said rolls and extending therebetween; a mechanical differential including a spider member; means connecting the arms of said differential in driving relation to said rolls; a first drum rotatably unitarily with said spider member of said difierential; a second and smaller drum freely pivoted on a fixed axis and aligned with said first drum; and a low rate spring having a natural radius less than that of said second drum wound about said drums to apply torque to said first drum, so that when the tension in said strip falls below a desired value determined by the characteristics of said spring,

said rolls are driven to restore the tension in said strip to said desired value.

5. Apparatus of the class described comprising, in combination: a supply roll; a takeup roll; a drive roll; a record strip passing from said supply roll around said drive roll to said takeup roll; motor means for operating said drive roll to draw said strip from said supply roll; a constant torque motor; and means oppositely connecting said constant torque motor to said supply roll and said takeup roll to maintain in said strip a uniform tension determined by the torque of said torque motor.

6. In apparatus for converting information, a plurality of switches, a similar plurality of extensible and retractible pins each connected to an associated switch for operation thereof, means for biasing each of said pins in one direction, means for moving said pins in an opposite direction and against said biasing means and including a motor, and means operatively connected to said motor for equalizing the biasing effect of said biasing means and thus minimizing variations in the torque requirements and speed of said motor.

7. In apparatus for converting information, a plurality of switches, a plurality of retractible operating pins each connected to a switch and each biased in one direction, means for retracting said pins to a predetermined position, said retracting means including a motor, and torque balance means including a non-linearly loaded spring means operatively connected to said retracting means in a manner to minimize variations in the power requirements of said motor.

8. In apparatus for converting information, a plurality of switches, a plurality of retractible operating pins each connected to a switch and each biased in one direction, means permitting a portion of said pins to operate the switches associated with said portion of said pins, means for first retracting said portion of said pins and then the remainder of said pins to a predetermined position, said retracting means including a motor, and torque balance means including a non-linearly loaded spring means operatively connected to said retracting means in a manner to minimize variations in the power requirements of said motor.

9. Apparatus of the class described having a motor operating through a cam system to move a plurality of spring biased pins into and out of operating position and exerting a variable load torque dependent on the position of said pins on said motor; means for applying a counter torque of substantially equal and opposite effect to said motor, said counter torque means comprising an eccentric mechanically connected to said motor, a first spring biased lever applying a force to said eccentric through an eccentric follower attached to said lever intermediate its ends, a second spring attached to said eccentric for applying a variable and intermittent force thereto, said springs being such that the load torques applied to said eccentric balance said first load torque, said motor having a minimum and substantially uniform load torque as a result thereof.

10. Apparatus of the class described, comprising in combination: a shaft; drive means normally providing a first torque about said shaft in a single direction to cause unidirectional rotation thereof; a cam follower; cam means carried by said shaft and presenting to said follower a rise portion followed by a fall portion as said rotation takes place; a load device connected for operation by said follower so as to continually urge said follower against said cam means, whereby during the rotation of said shaft accompanying said rise portion of said cam means a second torque is supplied in said load device which is of the opposite sense to the said first torque supplied by said drive means, while during the further rotation of said shaft accompanying said fall portion of said cam means the said second torque is of the same sense as the said first torque supplied by said drive means and means connected to said shaft for applying a third torque thereto which is equal and opposite to the said second torque during both the said rise and fall portions of said cam means, whereby to render the load on said drive means more uniform throughout the entire rotation of said shaft.

References Cited in the file of this patent UNITED STATES PATENTS 469,652 Jennings Feb. 23, 1892 1,166,030 Willower et al. Dec. 28, 1915 1,952,904 Bootwick Mar. 27, 1934 1,996,815 Kimpton et al. Apr. 9, 1935 2,389,047 Heiny Nov. 13, 1945 2,392,226 Butterworth et al. Jan. 1, 1946 2,517,055 Thompson Aug. 1, 1950 2,532,228 Hesh Nov. 28, 1950 FOREIGN PATENTS 313,672 Great Britain June 20, 1929 647,545 Great Britain Dec. 13, 1950 

